Various components in an engine's exhaust system such as exhaust conduits and emission control devices may become thermally degraded via high temperature exhaust gas, to reduce the temperature of the exhaust gas cooling systems have been incorporated into engines. For example, coolant jackets have been integrated into engine cylinder blocks and cylinder heads. The coolant jackets may be configured to reject heat from the engine. However, under certain operating conditions coolant jackets may not provide the desired amount of exhaust gas cooling. Therefore, high temperature exhaust gas may flow into the exhaust system from the engine and thermally damage various components such as exhaust conduits, catalysts, filters, etc.
U.S. Pat. No. 5,873,330 discloses an outboard marine engine that provides coolant to components downstream of the cylinder head. The engine includes a series of coolant passages surrounding a plurality of exhaust runners and an exhaust manifold. The inlet of the coolant passages is adjacent to a first outer exhaust runner and the outlet of the coolant passages is adjacent to a second outer exhaust runner. This coolant passage configuration flows coolant around the first outer exhaust runner, around the inner exhaust runners, and then around the second outer exhaust runner. Thus, coolant sequentially flows around each of the exhaust runners. Additionally, the general flow of coolant in the coolant passages is substantially perpendicular to the flow of exhaust gas through each of the exhaust runners. Furthermore, the cooling system disclosed in U.S. Pat. No. 5,873,330 draws water into the cooling system from the surrounding marine environment and expels water from the cooling system into the surrounding marine environment.
The Inventors have recognized several drawbacks to the engine cooling system disclosed in U.S. Pat. No. 5,873,330. When coolant is successively flowed around each of the exhaust runners, uneven cooling of the exhaust runners may occur. Moreover, when the coolant is flowed around the exhaust runners in a direction that is substantially perpendicular to the exhaust gas flow, the variance in exhaust runner cooling is exacerbated due to the flow pattern generated by such a configuration. As a result, the exhaust runners and the exhaust manifold may experience warping, as well as other types of thermal degradation. Furthermore, the cooling system disclosed in U.S. Pat. No. 5,873,330 may not be applicable to vehicles designed for land travel which cannot draw water from their surrounding environment.
As such in one approach, an engine exhaust component is provided. The engine exhaust component may include a plurality of coolant passages having parallel coolant flow, each coolant passage at least partially surrounding a respectively corresponding exhaust runner. The engine exhaust component may further include a coolant inlet manifold coupled to each of the coolant passages and a coolant outlet manifold coupled to each of the coolant passages.
In this way, coolant may be separately flowed around the exhaust runners and the parallel flow configuration decreases cooling variability between the exhaust runners. As a result, the likelihood of warping of the exhaust runners is reduced.
This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Furthermore, the claimed subject matter is not limited to implementations that solve any or all disadvantages noted in any part of this disclosure.